Recurring events with timezone

Hendrik Helwich h.helwich at
Tue Oct 19 13:26:33 CEST 2010

Am 19.10.2010 10:08, schrieb Joon Radley:
> Could you please give an example of the bug that needs to be fixed?
> Could you please explain how converting from locale ->  UTC ->  locale is better than just converting from UTC ->  locale?

Hi Joon,

ok a small example: Assume i am in the german time zone (UTC+2 in summer 
and UTC+1 in winter) and want to start from today a monthly infinitely 
recurring event from 10-12 o'clock.
Kontact creates a the following xml (i removed some tags):

<?xml version="1.0" encoding="UTF-8"?>
<event version="1.0" >
<product-id>KOrganizer 3.5.9 (enterprise35 20100805.1161816), Kolab 
<recurrence cycle="monthly" type="daynumber" >
<range type="none" ></range>

Kontact now shows this event starting at 10 o'clock also in november of 
this year. But there is a different time offset in germany in november 
so it should be shown at 9 o'clock instead if a correct UTC -> local 
conversion would be made here. It seems kontact is doing a UTC -> local 
on the start date of the event and assuming that the time offset does 
not change. So in november kontact shows that this event will start at 9 
o'clock UTC time.

But it gets more bad if i am in a different time zone now. Say i am an 
attendee of this event and i live in Johannesburg in South Africa. The 
time offset there is UTC+2 all the year. If i switch my computer and 
Kontact to this time zone, Kontact also shows the start time at 10 
o'clock all the year. This means in november of this year the person 
from Johannesburg would be an hour to early at this meeting because the 
UTC time would be 8 o'clock there (at least in this case he will not 
miss it :-)  ).

This is an example of a problem that cannot be solved correctly without 
adding time zone information to the storage format.


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